"I want to be a scientist when I leave school."
"You're not smart enough. Look at those grades."
Knowledge is acquired over time, years and hard work. toi may not be smart enough at the moment, but that doesn't mean toi can't make your dream come true.
"I'd like to make a living as a writer."
"Don't bother. It's not good pay."
Is money plus important than happiness? écriture could be a side job if needs be.
"I believe in fées and unicorns."
"How old are toi really!?"
If something is real to you, then it exists. What about Jesus?
"You're 20 and you're still a virgin!?"
There is no set time for anything...